Module 8 Vocabulary

• Anti-dysrhythmic drugs – Medications used to treat or prevent abnormal heart rhythms (dysrhythmias).

• Atrial kick – The additional volume of blood pushed into the ventricles by atrial contraction before systole.

• Automaticity – The ability of cardiac cells to generate their own electrical impulses without external stimulation.

• AV node (atrioventricular node) – A cluster of cells in the heart that delays the electrical impulse before passing it to the ventricles, allowing for coordinated contraction.

• Bradycardia – A slower-than-normal heart rate, typically below 60 beats per minute.

• Bundle branches – Pathways that conduct electrical impulses from the bundle of His to the left and right ventricles.

• Bundle of His (AV bundle) – A collection of heart muscle fibers that transmit electrical impulses from the AV node to the ventricles.

• Conductivity – The ability of cardiac cells to transmit electrical impulses.

• Defibrillation – The delivery of an electric shock to the heart to restore normal rhythm in cases of life-threatening arrhythmias.

• Dysrhythmia/Arrhythmia – An abnormal heart rhythm.

• Electrocardiogram (EKG/ECG) – A test that records the electrical activity of the heart.

• Electronic pacemaker – A device that sends electrical impulses to the heart to regulate its rhythm.

• Fibrillation – Rapid, irregular heart contractions that reduce the heart’s ability to pump blood effectively.

• Normal sinus rhythm – The normal rhythm of the heart, originating from the sinoatrial (SA) node.

• P wave – The part of an ECG representing atrial depolarization (atrial contraction).

• Premature ectopic beat – An early heartbeat originating from outside the normal conduction pathway.

• Purkinje fibers – Specialized fibers that distribute electrical impulses through the ventricles, triggering contraction.

• QRS complex – The part of an ECG representing ventricular depolarization (ventricular contraction).

• R-R interval – The time between two consecutive R waves on an ECG, used to measure heart rate.

• Reentry mechanisms – Abnormal electrical conduction patterns that can cause arrhythmias.

• Refractory period (absolute and relative) – The period during which the heart muscle cannot respond to another electrical stimulus (absolute) or can only respond to a very strong stimulus (relative).

• SA node (sinoatrial node) – The heart's natural pacemaker, located in the right atrium.

• Supernormal excitatory period – A brief period when a weaker-than-normal stimulus can trigger a heartbeat.

• T wave – The part of an ECG representing ventricular repolarization (recovery phase).

• Tachycardia – A faster-than-normal heart rate, typically above 100 beats per minute.

Respiratory 1:

• Affinity of hemoglobin for oxygen – The strength with which hemoglobin binds to oxygen, affecting oxygen transport.

• Air-trapping – Retention of air in the lungs due to airway obstruction, commonly seen in conditions like COPD.

• Airway resistance – The opposition to airflow in the respiratory tract, influenced by airway diameter.

• Alveolar-capillary membrane – The thin barrier between alveoli and capillaries where gas exchange occurs.

• Alveolar cells (type I and II) – Type I cells facilitate gas exchange; Type II cells produce surfactant to prevent alveolar collapse.

• Alveoli – Tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged.

• Atelectasis – Partial or complete lung collapse due to alveolar deflation.

• CO₂ + H₂O ⇌ H₂CO₃ ⇌ HCO₃⁻ + H⁺ – The carbonic acid-bicarbonate buffer equation, which helps regulate blood pH.

• CO₂ narcosis – A condition in which high CO₂ levels suppress respiratory drive, often seen in COPD.

• Conducting airways – The airways (trachea, bronchi, bronchioles) that transport air but do not participate in gas exchange.

• Cyanosis – A bluish discoloration of the skin and mucous membranes due to low oxygen levels.

• Dead air space – Areas of the respiratory system where no gas exchange occurs.

• Diffusion – The movement of gases (O₂ and CO₂) across the alveolar-capillary membrane.

• Gas exchange – The process of O₂ entering the blood and CO₂ exiting the blood in the lungs.

• Hypercapnia – Excess carbon dioxide in the blood, often due to hypoventilation.

• Hypoxia – Insufficient oxygen supply to tissues.

• Lung compliance – The lung’s ability to expand and recoil.

• Mucociliary blanket – A layer of mucus and cilia that helps trap and remove debris from the airways.

• Oxygen saturation (SaO₂ or O₂ sat) – The percentage of hemoglobin molecules bound to oxygen.

• PO₂ – Partial pressure of oxygen in the blood.

• PCO₂ – Partial pressure of carbon dioxide in the blood.

• Partial pressure of a gas – The pressure exerted by a specific gas within a mixture of gases.

• Perfusion – The process of delivering oxygenated blood to tissues.

• Pleura – The double-layered membrane surrounding the lungs.

• Pleural space – The small space between the pleural layers containing lubricating fluid.

• Pleuritic chest pain – Sharp chest pain caused by inflammation of the pleura, worsened by breathing.

• Pleuritis/Pleurisy – Inflammation of the pleura, causing chest pain.

• Pneumothorax – Air in the pleural space, leading to lung collapse.

• Pulmonary embolism (PE) – A blockage in a pulmonary artery due to a blood clot, fat embolism, or air embolism.

• Respiratory center – The brainstem region that controls breathing.

• Respiratory failure – Inadequate gas exchange leading to dangerously low oxygen or high carbon dioxide levels.

• Shunt – A condition where blood bypasses ventilated alveoli, leading to impaired oxygenation.

• Surface tension – The force that tends to collapse alveoli, counteracted by surfactant.

• Surfactant – A substance secreted by Type II alveolar cells that reduces surface tension and prevents alveolar collapse.

• Ventilation – The movement of air in and out of the lungs.

• Ventilation/perfusion (V/Q) mismatch – A condition where airflow (ventilation) and blood flow (perfusion) are not properly matched, leading to inefficient gas exchange.